Announcing a Special Issue on Elasmobranch Behaviour!

When I discovered sharks in the turquoise Tahitian lagoons, I was fascinated by their complex and clearly intelligent responses in different situations. Based on what I saw myself, I figured they were more intelligent than dogs. But later, when I got an internet connection, I was shocked to learn that science had not noticed!

By then the community I had watched for years was being slaughtered for shark fin soup, so I wrote down the story of my beloved thoughtful sharks in my first book, The Shark Sessions.

Since then I have been trying to publish my findings scientifically, which has been a real challenge for an isolated wildlife artist. However, two years ago, an editor of the journal Behaviour was taken with my writing and invited me to organize a Special Issue on my favourite subject: Elasmobranch behaviour and cognition. It was a real learning experience for me and I was lucky that shark Ethologist Professor A. Pete Klimley offered to help. Not only did his advice serve as a valuable guide in a variety of ways, but his writings have wonderfully enhanced the issue. 

Anyway, I am thrilled, today, to be able to tell you that this Special Issue has finally been published! It is organized into three main themes—Historical Articles, Behaviour, and Cognition—each contributing to a deeper understanding of elasmobranchs’ lives and challenging prevailing misconceptions.

Historical Articles

The issue opens with a groundbreaking review by Guest Editor A. Peter Klimley et al.: a comprehensive ethogram for chimaeras, sharks, and rays. Ethograms are essential for describing animal actions in their natural habitats and this work was done to aid researchers to characterize future sightings as well as to standardize terminology for future research. Klimley is an ethologist in the line of Nikolaas Tinbergen, Konrad Lorenz, and Arthur A. Myrberg Jr., his former professor, who worked for several years with Lorenz in Europe. Klimley carries their legacy forward by creating an ethogram for the entire group of chondrichthyan fishes, and challenging the notion of sharks as simple feeding machines.

Two historical studies, also by Klimley, follow. The first dives into the social interactions of hammerhead sharks, revealing a complex world of social competition and mating behaviours. Female scalloped hammerheads, for instance, engage in a Cork Screw display to establish dominance, while males use Torso Thrust to compete for mating opportunities. Klimley's study on white sharks unveils agonistic displays and ritualized behaviours, challenging traditional stereotypes of sharks as mindless predators.

 

It is followed by a critical commentary by myself, which questions the validity of the study that claimed to have found dominance-subordination hierarchies in the smooth dogfish. It thus challenges prevailing notions about shark social dynamics.

“The Mistaken Identity Hypothesis for shark bites on humans is an anthropomorphic fallacy” by Eric Emile Germain Clua Ph.D., DVM, delves into the reasons behind the widely accepted hypothesis that sharks mistake swimmers for prey items. Clua proposes a “Natural Exploration Hypothesis,” suggesting that observed shark behaviour, including bites on humans, is a response to the sharks’ natural tendency to strike moving objects at the surface, rather than a case of mistaken identity.

Behaviour

The Behaviour section is introduced by my own ethogram for Blacktip Reef Sharks, which describes 35 context-specific behaviour sequences. It not only highlights the flexibility in the behaviour of these sharks but also reveals their large individual differences. The behavioural repertoire offers intriguing clues as to the complexity of the sharks' cognitive functions.

 

The study is, however, disrupted by the arrival of the shark fin industry, which underlines the devastating impact on shark populations of this largely criminal trade.

“Insight into manta ray behaviour using animal-borne Crittercams” by Nicole Pelletier et al. sheds light on the behaviour of manta rays in their natural habitats. The study reveals the importance of social behaviour for these filter-feeding elasmobranchs, with the reef manta ray exhibiting more pronounced social interactions than the giant oceanic manta ray. The study documents new inter-specific interactions between these two species as well as courtship events.

The article “Could convulsive body shuddering of a white shark near a shark cage be an element of a threat display?” by Pete Klimley and Mauricio Hoyos-Padilla challenges common stereotypes by examining the agonistic displays of a male white shark near a shark cage. The study emphasizes that even these formidable marine predators display ordinary animal behaviours in response to perceived threats, debunking the sensationalized portrayals in popular media.

Cognition

The Cognition section challenges the historical dismissal of elasmobranch mental capacities. Vera Schluessel et al.’s paper, “When the penny drops: sharks outsmart cichlids in serial reversal learning” sets the tone by testing two species—eight cichlids and seven bamboo sharks—in a reversal learning task. The results showcase the sharks’ capacity for learning and behavioural flexibility, challenging the perception of elasmobranchs as instinct-driven creatures.

“Examining individual behavioural variation in wild adult bull sharks (Carcharhinus leucas) suggests divergent personalities” by Thomas Matthieu Vignaud et al., takes an ethological approach to analysing boldness-shyness and aggressiveness-placidity in adult bull sharks. The study not only characterizes individual shark personalities but also quantifies the differences in behaviour over time, emphasizing the variation among individuals.

The article “Long-lasting memory of a free-ranging top marine predator, the Bull shark Carcharhinus leucas” by Clémentine J. M. Séguigne et al. explores the memory capabilities of sharks. Given their long lifespans, sharks are expected to have good long-term memories, and this study provides evidence supporting this hypothesis. The sharks quickly resumed their attendance when feedings resumed following interruption of shark feedings due to the COVID-19 pandemic.

The Special Issue concludes on a note of mystery with “Shark evacuation from Mo’orea Island in 2002” by Ila France Porcher. The article recounts a unique event where all Blacktip Reef sharks and likely other species left their lagoon and ocean ranges for two weeks, thus evading human view without any apparent explanation. The mystery underscores the gaps in our understanding of elasmobranchs' lives and behaviours.

In summary, this Special Issue not only unveils the behavioural complexity of elasmobranchs but challenges prevailing stereotypes, emphasizing the need for their conservation. The revelations in this collection are poised to inspire further studies and advocate for robust measures to try to  safeguard these ancient underwater inhabitants from the current intensive ongoing exploitation.



Comments

Post a Comment

Popular posts from this blog

Letter to the Discovery Network

Image
To the Discovery Network: Members of our Internet shark discussion forum, SHARK-L, have been asked by your marketing representatives to help promote your famous Shark Week sequence. This letter, signed by list members and friends, is our formal response to the request from your grass roots agency, New Media Strategies, for our support of the programming. How can we support Discovery Channel when we are fighting for shark conservation, and its biggest obstacle is the monster image given to sharks by the media, including Shark Week programs? Further, some of us who have been directly involved in the production of your documentaries feel disgusted at the way that our interviews were censored and our words twisted around. Our group is comprised of scientists, researchers, educators, media companies, and many NGO's, lobbyists and others. In aggregate we represent a strong network of influence that can help or hurt the efforts of any Shark related programming or initiatives. In...
Read more

On the gestation period of the blackfin reef shark, Carcharhinus melanopterus in waters off Moorea, French Polynesia

Image
Originally published in the Journal "Marine Biology" at: http://link.springer.de   Abstract Underwater visual and photographic observations, over a four year period, monitored the presence of mating wounds on female Carcharhinus melanopterus . Mating begins in November and continues until the end of March as each female follows her own temporal cycle. Correspondingly, parturition begins in September and continues until January. Each female again mates 1.5 to 2.5 months after parturition, thus completing an annual reproductive cycle. The gestation period is 286 to 305 days, with slight individual differences. All resident sharks under observation followed this pattern. Evidence of reproductive events presented by transient females conformed with the pattern of the residents. Introduction The few studies postulating a gestation period for the reef blackfin shark Carcharhinus melanopterus have varied greatly in their conclusions. Based on an examin...
Read more

SHARKS DON'T BITE like we do

Image
Though sharks have gained a mythical reputation for being biters, their behaviour in nature is the opposite of what we would expect from the vicious animals depicted in the media. I had many opportunities to observe sharks under circumstances in which I expected them to bite, as a dog, cat, horse, or bird would tend to do. Yet they did not.  All other species, wild and tame, with whom I had the intimacy I shared with sharks, had bitten me sooner or later, either by accident or in a fit of pique; even my pet dog sometimes grabs my hand in her teeth along with the offered cookie.  Further, while the blackfin reef sharks I knew enjoyed roaming with favourite companions, I never saw them fighting with each other. They had friends but no enemies ! For years people had told me, and I half believed myself, that one evening I would be bitten and would bleed to death, or faint and drown. Since I was alone far from shore as night was falling, I could expect no one to...
Read more